First, not all instruments in HALion support true Note Expression. I’m not currently aware of a way to ‘add’ that support to an instrument program in Sonic 3 (Though I know you can in full blown HALion 6). The good news is that you can still automate your stuff a variety of different ways, and you can keep such automation in ‘note expression containers’ in your Key MIDI Editor.
I’d most definitely use Note Expression containers as opposed to using a direct VST automation lane.
If you cut/copy and paste, or otherwise nudge/move a note, the expression data moves with it during the process.
If you quantize or apply groove templates to the notes, the expression data moves with each individual note.
Of course it can depend on the style and complexity of the part(s) if it’s truly a better workflow…if it’s detailed through composed orchestration with all sorts of subtle articulation information…chances are that automating via CC and having the option of keeping things in note expression containers will be worth it!
Here is an alternative method to working with VSTi automation lanes. It works via CC automation instead of using the VST automation lanes. One advantage to this method is that you can keep up with it all in the MIDI part itself if you like.
You can also apply it to individual notes as if it were note expression (I.E. Double click a note in the Key Editor, and draw the CC event(s) in). Technically it’s still CC events instead of true note expression, but they get packed into note expression containers that will move with the notes (I.E. if you quantize, or copy/paste, etc.), so you can still enter them this way. Tools exist in the MIDI menu of CuBase to dissolve that style of keeping CC events down to the CC lane of the MIDI part, or even extract them to the track lanes if you should ever need to do that. Tools also exist to convert MIDI controllers into Note Expression.
Personally I typically work in the CC lane of the Key MIDI editor because it’s easy to see at all times. If I ever want to quantize or copy/paste a bunch of stuff, I’ll convert it back and forth between note expression and lane data as it suits me.
If the control you wish to automate is also assigned to a knob in the Quick Control set, those will also respond to CC messages. Here is a list of how it is all laid out by default:
Automation and Factory MIDI Controller Assignment (From Sonic 3 OM)
Automation and Factory MIDI Controller Assignment (From Sonic 3 SE OM)
If you want to automate something directly from the Macro page of an instrument that is NOT assigned to a QC knob, then right click the control in HALion you wish to automate and ‘learn’ a CC (move a fader on your keyboard). (Sonic 3 OM Reference)
From there you could drive that control via the learned CC message. You can keep them in the MIDI part itself, or on a track CC automation lane.